DTD versus XSD

Will DTD's disappear in the future? I have often heard about XSD's being the DTD's of the future, but when you have to write an XSD for HTML for instance, it wil be more than twice as big as the DTD for the same purpose. It's true that the DTD will be less defined, but is that really necessary for such definition?

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: Will DTD's disappear in the future? I have often heard about XSD's being the DTD's of the future, but when you have to write an XSD for HTML for instance, it wil be more than twice as big as the DTD for the same purpose. It's true that the DTD will be less defined, but is that really necessary for such definition?: Hi,

Well for one DTDs are not really a part of XML. They jsut do not follow XML scheme of representing things, in other words DTDs do not follow XML syntax. Secondly there are many things that DTDs can just never let you specify as a document definition. For example:1) You cannot derive an element from another. For ex, you cannot say address can be derived as a combination of Street Address, City, and State.2) DTDs do not support data types. Well this is self descrptory. A fall-out of this is that you cannot set ranges etc, which is normally associated with data types.

So as you can see XSDs are not an overhead but are real necessities for proper XML document definition.